Monday, August 16, 2010

The original plan for my wind direction finder was to begin with a wired system, then graduate to a wireless system, but after learning more about wireless transmitters and because of the clear advantages of going wireless, I decided to jump right into a wireless system and include a full graphical LCD as well. This new setup will require two micro controllers, one for the sensor and transmitter and one for the receiver and display panel. I'll be using 2.4GHz Xbee modems to transmit and receive sensor data and a KS0108 128x64 liquid crystal display. Now that the system will be made wireless, the transmitter at the top of the mast will have it's own separate battery, making power conservation a more important factor to consider. I've implemented new code between the micro controllers that allows the transmitter to be turned off and on remotely as needed. While the transmitter will still consume a small amount of power "listening" for the signal to turn on again, it should save conserve battery power and allow the transmitter to remain "asleep" when the boat is being set up and taken down, or when wind direction information is not needed. Once the display and additional micro controller have arrived in the mail, I'll begin construction and further iterations of the code.

The micro controller (using Atmega328 chip) requires 5v to run which is an odd voltage to produce using 1.5v alkaline's or 3.7v lipo cells. I'll be using a voltage booster to boost 3v from two AAs to the 5v required at about 85% efficiency. With a current draw of 60 -70ma this should give a 36+ hour continuous runtime (no sleep mode) while maintaining a small form factor and convenience of AAs.